Peptoids
We have discussed biomimetic systems with special emphasis on vesicles inspired by cell membranes and viral envelopes. At this point we turn our interest on describing mimics of proteins and DNA. The first of these, the poly N-substituted glycine , peptoid, was developed in a combinatorial drug discovery program by Simon and coworkers 70,71 , and its chemical structure is described in Figure 3.4. The general chemical structure of polypeptoids was inspired by polypeptides, with the difference...
Dispersion from Porous Silicon
Soon after the first reports of visible PL from electrochemically etched porous silicon, Heinrich et al. 32 reported the preparation of luminescent colloidal suspensions of silicon particles by ultrasonic treatment of photoluminescent porous silicon. The porous silicon particles that resulted ranged in size from individual nanocrystals several nanometers in diameter to much larger porous structures many microns in size . Bley and coworkers subsequently improved and optimized the anodization...
Virosomes
A key issue in the development of second-generation vaccines involves targeting and delivery of antigens to antigen-presenting cells APCs . Remarkable advances have been achieved in vaccine preparation techniques and among them, virus-mimicking nanoparticles virosomes have demonstrated potency in eliciting immune responses while minimizing side effects. The term virosome was coined by Almeida et al. 44 in 1975 due to the unexpected finding of a viruslike structure during the visualization of...
Ab Initio and Semiempirical Quantum Chemistry
In order to eliminate any fundamental dependence on the assumed potential model, one must resort to the more complicated and time-consuming methods of quantum chemistry. Whereas clearly these techniques in theory provide the correct treatment of molecular and atomic systems, incomplete basis sets and limitations due to electron correlation or exchange for the methods capable of treating reasonably sized molecules can present considerable complications. In the present case, we are primarily...
Double Effective Medium Model for the Optical Properties
Various groups have tried, with mixed success, to explain the optical properties of thin films formed from organically cross-linked gold nanoparticles mainly for LBL films .20,28 The optical properties of the films can be described with a two-step EMA.33,39 Two steps are needed because three phases are present in the film the gold particles, the molecules, and voids, and because of the way they are distributed. The presence of the voids could be vaguely seen in previous SEM, scanning tunneling...
Comparison of 3D STEM with TEM Tomography for Biology
3D STEM is a 3D technique for the imaging of whole assemblies, as is tilt-series TEM, in contrast to the averaging techniques using diffraction from crystals or multiple images ofidentical objects. The resolution of the tomogram obtained in a tilt series both on cryo and embedded or stained is typically 5-10 nm in xyz 36-40 . From our calculations it follows that 3D STEM with the present microscopes already has approximately the same resolution 4 x 4 x 7 nm on a conventional thin section....
V
FIGURE 3.1 Structurally inspired biomaterials. Liposomes, virosomes, and polymersomes are examples of simple cell mimics without internal contents. They have been used for vaccines and targeted drug delivery systems. Peptide nucleic acids mimic both proteins and DNA, and peptoids are mimics of proteins. FIGURE 3.2 Functionally inspired biomaterials. Mussels and barnacles secrete proteinaceous bioglues for holdfasts on both organic and inorganic surfaces in aqueous environments....
H
photoluminescent silicon nanocrystals, though most of them have not been demonstrated. Here, we briefly review biologically relevant examples of hydrosilylation, in roughly chronological order. In 1997, Wagner et al. 93 reported biofunctionalization of self-assembled monolayers SAMs of 1-octene formed by hydrosilylation of an H-terminated Si 111 surface. They used 254 nm UV-initiated hydrosilylation to form a dense monolayer of 1-octene on the wafer surface. They then used two different...
MusselAdhesive Proteins
The harsh living conditions of the seashore, the impact of strong waves, and the buoyant force of water turn out to be selective forces in evolution. Only organisms that developed strategies for holding tightly to surfaces survived. The science of the mussel's strong adhesion was the subject of famous work done by Brown in 1952 90 , and later, Waite and Tanzer made a major breakthrough 91 . In their study, they found that MAPs in threads and plaques have extensive amount of posttranslationally...
Applications of Silicon Nanoparticles in Biophotonics
Actual applications of free silicon nanoparticles in biophotonics are still in their infancy. There are two recent reports in which silicon nanoparticles were surface functionalized to make them water dispersible and then used to image cells via fluorescence microscopy. Li and Ruckenstein 103 attached acrylic acid to red-emitting nanoparticles that had been produced by vapor-phase laser pyrolysis followed by solution-phase etching. They incubated fixed Chinese hamster ovary CHO cells with an...
Application of Bimetallics
The alteration in collective electronic, optical, and magnetic properties of organized nanoensembles for bimetallics over their monometallic counterpart is increasingly the subject of investigation 98 leaving catalytic applications aside 3,98-100 . It has the potential to be used as a nonlinear optical material. Possible future applications include the areas of ultrafast data communication and optical data storage 3-4,101 . Such materials would be useful in developing nanodevices e.g.,...